I. Sosna - Department of Horticulture, Faculty of Agriculture, Wroclaw University of Environmental and Life Sciences, pl. Grunwaldzki ۲۴ A, ۵۰-۳۶۳ Wrocław, Poland.

The purpose of this research was to assess the influence of several orchard systems involving trees trained to different leader numbers on growth, cropping, and fruit quality of two apple cultivars. The study was conducted during ۱۹۹۴-۲۰۰۷ at the Fruit Experimental Station in Samotwór, next to Wrocław (south-western Poland). One-year-old trees of ‘Elstar’ and ‘Jonagold’ cultivars on the M.۹ rootstock were planted in the spring ۱۹۹۴ using ۳.۵ m spacing between rows and a variable in-row spacing: ۲.۴ m (Mikado-four leaders), ۱.۸ m (Drilling-three leaders), ۱.۲ m (Tatura-two leaders), and ۰.۶ m (Güttingen-V-one leader). In this way, the number of leaders per hectare was almost the same, regardless of the system. The most vigorous growth occurred on the most sparsely planted trees under the Mikado system, whereas the Güttingen-V apple trees developed thinnest shoot systems. The bloom abundance registered in the ۲۰۰۴-۲۰۰۷ periods was more related to the year, rather than to the planting system. The ۱۹۹۵-۲۰۰۷ total per-tree yield was decreasing as the planting density increased. When yield per hectare was considered instead, the Güttingen-V system still produced the lowest. As the trees aged, the quality of apples diminished-possibly as a result of increasing tendency toward biennial bearing. In the last years of the study (۲۰۰۳-۲۰۰۷), the trees with the largest numbers of leaders, i.e. Mikado and Drilling, showed the most irregular yielding patterns. The orchard planting system had no significant influence on the fruit mean weight.

Biennial bearing, fruit quality, Training system